U.S. Pat. No. 5,208,052 (SCHMIDT et al.) discloses a hot runner nozzle assembly including a mold assembly with a mold cavity therein, an inlet port in the mold assembly communicating with the mold cavity, an injection nozzle for delivering molten resin to the inlet port and an insulating sleeve positioned around the nozzle between the mold assembly and nozzle insulating the nozzle from the mold assembly.
U.S. Pat. No. 7,481,649 (GAILLARD) discloses an injection molding apparatus that includes a hot runner and a mold. The hot runner includes at least one nozzle that engages a nozzle-receiving cavity of the mold. The molding apparatus further includes a nozzle sleeve surrounding a portion of the nozzle and having a nozzle-sealing opening that receives the nozzle. The nozzle sleeve is movably secured to the hot runner or the mold so that when the mold is removed from the hot runner, the nozzle sleeve remains secured to the corresponding part of the apparatus. When the mold and hot runner are engaged with one another, the nozzle sleeve is springingly urged into sealing engagement with a sealing surface of the nozzle receiving cavity of the mold.